Two categories of system are known for that purpose, namely:
those that provide handling from the deck of a maritime support to the outside of said support, in discontinuous manner, with first means comprising a set of winches, cables, and gantries enabling the load to be raised off the deck of the ship and then moved overboard therefrom, and finally put into the water, and another means comprising a second set of winches and cables for implementing all of the operations that take place at sea or underwater: which systems require one of the means to take over the load from the other, and for that purpose it is necessary to make use either of divers who perform the transfers (which is dangerous and chancy depending on the state of the sea), or else it is necessary for the two above-mentioned systems to be associated with additional mechanical devices that must also be provided on the loads proper, said devices serving to eliminate human intervention but often being very complicated, difficult to operate, and very large, particularly with increasing weight of the load; and PA1 those that perform both aspects of handling as defined above, i.e. both in the air and on or in the sea, in a single pass: such systems comprise special moving gantries having a large amount of clearance, of the order of 160.degree. of oscillation about a horizontal axis secured to the support, and constituted by a structure that is thus driven about said axis by at least four large actuators: naturally, such gantries are very heavy, very bulky, and pose problems firstly of stability of the ships carrying them, and secondly of taking up forces at points that are highly localized and very close to the edges of such ships, thereby requiring specialized ships, and in addition they require very large investment costs. PA1 the function of using a load, in particular marine or submarine vehicles such as remotely-controlled vehicles, or plows, after they have been immersed; and PA1 the function of hoisting them from the deck of a support at sea until they are launched, and vice versa; and PA1 that must be done without using means that are too bulky, too heavy, or too complex to implement, or that require highly specialized devices, so as to avoid worsening the overall investment cost, while nevertheless providing both of the above functions with a high degree of safety and of effectiveness.
The problem posed is to be able to perform two complementary functions that are both required for handling loads at sea, but which have opposing criteria and requirements, namely: